Etanercept does not have an apoptosis-inducing effect on psoriatic keratinocytes

Tumor necrosis factor-alpha is the key inflammatory cytokine in psoriasis vulgaris triggering abnormal differentiation and proliferation of keratinocytes. Etanercept as an antitumor necrosis factor-alpha agent is widely used for the treatment of psoriasis vulgaris.

To find out whether etanercept has an apoptotic effect on psoriatic keratinocytes.

Biopsies from 13 untreated chronic plaque psoriasis patients and 10 control subjects were examined in the study. Immunohistochemical staining for Ki-67 and the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) method for the detection of apoptosis were performed. Ki-67 and TUNEL indices were calculated.

The mean Ki-67 index of patients before treatment (34.20 +/- 10.30) was significantly higher than that of the control subjects (8.30 +/- 2.20) and of the treated patients (9.50 +/- 2.50); however, it did not differ between the treated patients and control subjects (p < 0.001, p = 0.001 and p = 0.208, respectively). Although the mean TUNEL index of patients before treatment (0.23 +/- 0.44) was significantly lower than the controls (1.1 +/- 0.99), it did not significantly differ after etanercept therapy (0.46 +/- 0.66) (p = 0.030 and p = 0.083, respectively). The mean TUNEL indices of treated patients and control subjects were not different (p = 0.131).

Etanercept decreased epidermal thickness successfully without inducing apoptosis of psoriatic keratinocytes.